Method of recovering explosives in particular form



Patented Oct. 19, 1954 OFFICE METHOD OF REOOVERING EXPLOSIVES- IN PARTICULAR FORM Fredericlclt. Seavey, Alton, 111., assignor to 01in Industries, lnc., East Alton, 111., a corporation of Delaware No Drawing. Application February 10, 1951, Serial No. 210,429

5 Claims.

This invention relates to'a method of handling explosives and more particularly to a method of reclaiming explosives.

Inthe breaking down or disassembly of loaded ammunition it is common practice to segregate explosive, such as trinitrotoluene and cast cornpositions containing trinitrotoluene as the binding agent, by melting the explosive and removin it from the shells, bomb heads, and other containers. Various means have been proposed for shooting the melting of the explosive. For example, in some instances it has been the practice to ply the interior of such containers with a jet of a heating medium such as hot water or steam, or to immerse the-containers in hot water, the molten explosive being drained from the shell or otherwise forced therefrom. In some instances the molten explosive was then permitted to solidify by cooling and was in the form of large irregular shaped chunks containing water pockets and relatively unsuited. for subsequent treatment or handling. In other instances the molten explosive was poured. or extruded into molds designed to provide the recovered explosive with a useful shape. Such methods had the disadvantage that large quantities of molten explosive were handled and considerable hazard was encountered in operation of the valves utilized for controlling the flow of the molten explosive. Furthermore, there is a tendency for the molten explosive to adhere to the side walls of the recovery vessel making it difficult and dangerous to remove the explosive therefrom. When the explosive composition has been composed of ingredients of substantially different densities, there has been a tendency for the ingredients to more or less segregate and result in a highly non-uniform recovered product.

In order to obtain the recovered explosive in a more suitable form for subsequent use, it has also been proposed, for instance, to direct a jet of steam into the mouth of the explosive container with. its open end down to permit the molten plosive to flow from the container into an agitated cold water bath. Such methods have been attended by the disadvantages of high steam consumption per unit Weight of explosive recovered and excessive periods of time required to remove the explosive from the container. It has also been necessary to continuously cool the Water bath to compensate for the heat introduced by both the condensed steam and molten explosive. Furthermore there is a strong tendency for the chunks or particles of explosive to adhere to each other and to the side walls of the cooling bath making it diflicult to recover the explosive therefrom. In addition, the recovered explosive parti- 2 cles have entrapped Water and have been irregularly shaped and widely divergent in size, detracting from their usefulness.

It is therefore an object of this invention to provide an improved process for recovering in high yield explosives from shells, bomb heads, and other containers. Another object of the invention is to provide a process for recovery of fusible explosive in which the tendency of the explosive to adhere to the recovery vessel is substantially eliminated. Still another object is to provide a procsee for recovery of explosives in which segregation of the ingredients is' substantially avoided. A further object is to provide a relatively safe, economically efiicient process for converting explosives into a par culate relatively free-flowing explosive suitable for use as a blasting explosive and. the like. A still further object is to provide an improved process facilitating recovery of the ingredients from an explosive composition.

The foregoing objects and advantages as Well as others which will become apparent from the following detailed description are accomplished in accordance with this invention by placing the explosive in a water bath containing a protective colloid at a temperature above the melting point of the explosive, agitating the Water bath until the explosive is of the desired granulation, and thereafter cooling to a temperature below the freezing point of the explosive. The agitation tends tobreak up or subdivide the molten explosive and it has been found that the use of the protective colloid under such conditions not only prevents the explosive particles from sticking together and adhering to the walls of the vessel and reduces the time required for removing the explosive from the container, but also prevents segregation of the ingredients, where the explosive is composed of ingredients of different densities. The molten particles of explosive are more or less spherical in shape and their size is determined by the degree or violence of the agitation. Upon cooling the particles form a mass of granular, free-flowing explosive.

In operation, the explosive is placed in the hot water containing the protective colloid and the agitation of the bath is maintained preferably throughout the heating and cooling periods. When the explosive to be treated is in a container in cast form, the bath'in which the container is immersed is maintained above the melting point of the explosive until the explosive has dropped from the container, at which time the container may, if so desired, be removed from the bath. Whereas in prior processes there was a tendency for the molten material to adhere strongly both to the interior and exterior of the container, no such disadvantage is obtained with the process of this invention and the container may be lifted from the bath without any substantial amount of the explosive sticking to it. As soon as the explosive has been removed from the container and the desired particle size obtained with the agitation, the cooling of the bath is effected by very gradually adding cold water. The particles of explosive may then be freed of water by simple decanting or filtration and may be subsequently air or oven dried. Vigorous agitation while the explosive is molten results in relatively small particle size, whereas milder agitation results in larger particle side. For instance, explosive particles having an average diameter anywhere in the range from about 0.007 inch to 0.07 inch may readily be obtained by properly controlling the degree of agitation.

Any suitable protective colloid may be employed such as gum arabic, dextrin, starch and those derived from animal proteins and the like. Large amounts of the protective colloid are unnecessary and sometimes detrimental and it is preferred to use an amount in the range from about 0.005% to less than about 0.20% based on the weight of water in the bath. With explosives such as trinitrotoluene the temperature of the water bath is preferably maintained in the range from about 85 C. to about 98 C. during the melting and particle shaping period and is then cooled to less than about 70 C. to solidify the spheres of explosive. Although the amount of hot water utilized may be varied considerably, it is preferable to maintain the ratio of water to explosive in the range from about 5 to parts of water to 1 part of explosive. The free-flowing particles of explosive so formed are uniform in composition and well suited for charging into other containers, or for use alone or with other ingredients as blasting explosives and the like.

If the explosive treated in accordance with the process of this invention is composed of a number of ingredients and it is desired to subsequently separate such ingredients by extraction processes, the very small diameter particles obtained by vigorous agitation in accordance with this invention are well suited for the purpose.

Although the process of this invention may be utilized advantageously with any of the ordinary explosives having a melting point below and an explosion temperature above the boiling point of water, such as trinitrotoluene, tetrytol and the like, the process is particularly advantageous with explosives having ingredients of widely divergent densities, as exemplified by compositions containing 20% to 75% cyclonite, 5% to 25% aluminum dust, and 20% to 75% trinitrotoluene.

By way of further illustration following is a typical embodiment of the invention describing the recovery of a trinitrotoluene explosive composed of 34% cyclonite, 16% aluminum dust, and 50% trinitrotoluene, which is in cast form in cylindrical containers.

About 400 parts by weight of water was heated by means of steam to a temperature in the range from 35 C. to 90 C. and about 0.048 part of protective colloid derived from animal proteins was added. Agitators of the propeller type were utilized to maintain the bath turbulent throughout. The cylindrical containers holding about 100 parts by weight of explosive were then completely immersed in the bath with the open end down. A wire basket was disposed below the mouths of the containers and was adapted to hold unmelted explosive out of contact with the agitators in the bath, in order to increase the safety of the operation. After about fifteen minutes the explosive was completely out of the containers so that the containers could'be lifted from the bath. The explosive at this stage was in a partly molten condition and agitation and heating was continued for about thirty minutes to sixty minutes until all large chunks of the explosive were melted and broken up to the desired particle size. Cold water was then added to the bath to bring the temperature down in the range of from 60 C. to 70 C. and the solidified particles or granules of explosive were filtered from the solution to a water content of about 10% to 20%. The material was then dried for about 24 to 36 hours in a tray drier at 60 C. The granular product obtained was uniform in composition and density, and was in convenient free-flowing form suitable for incorporation in blasting explosives and the like. At a density of 1.1 to 1.2 grams per cubic centimeter in a 1%. inch by 8 inch cartridge, the granular explosive was sensitive to detonation by a standard No. 6 blasting ca and exhibited a detonation rate of 4570 meters per second. The particle size was such that about 9.0% was retained on a 40 mesh screen, about 6 .0% was retained on a mesh screen, about 10.0% was retained on a mesh screen, about 10.0% was retained on a 200 mesh screen, and about 4.0% passed through a 200 mesh screen, i. e. an average particle size such as to pass through a 40 mesh sieve.

While the invention has been described with particular reference to explosives obtained in the disassembly of ammunition, the process may be advantageously applied to recover explosives in particulate form from other sources. For instance, when the explosive is originally manufactured, the process of this invention may be used to recover or obtain it in the desired particulate form.

From the foregoing it will be apparent that the process of this invention is relatively simple, practical, highly efficient in character, and well adapted to accomplish the aforenamed objects and advantages. While certain specific details are set forth herein it should be understood that considerable modification can be made therein without departing from the spirit and scope of the invention as set forth in the appended claims. Having thus described the invention, what is claimed as new and is desired to be covered by Letters Patent is:

1. The method of recovering water-insoluble explosives in particulate form which comprises suspending the explosive substantially free of volatile solvent in an agitated water bath at a temperature above the melting point of the explosive and containing 0.005 to 0.20 part by weight of a protective colloid for each 100 parts water to prevent the resultant adjacent particles of molten explosive from agglomerating, cooling the bath while maintaining the agitation to a temperature below the freezing point of the explosive, and thereafter separating the resulting solidified particles of explosive from said bath.

2. The method of recovering water-insoluble explosives in particulate form which comprises immersing the explosive substantially free of volatile solvent therefor in a water bath containing 0.005 to 0.20 part by weight of a protective colloid per each 100 parts water at a temperature above the melting point of the explosive maintaining said bath at such temperature until the explosive is molten and, agitating said bath to form the melted explosive into small particles, cooling the bath to a temperature below the freezing point of the explosive while maintaining the agitation, and thereafter separating the resulting solidified particles of explosive from said bath.

3. The method of recovering water-insoluble explosives in particulate form which comprises immersing the explosive substantially free of volatile solvent therefor in an agitated water bath containing 0.005 to 0.20 part by weight of a protective colloid per each 100 parts water at a temperature above the melting point of the exi plosive until said explosive is molten, thereafter while maintaining the agitation cooling the bath to a temperature below the freezing point of the explosive and separating the resulting solidified particles of explosive from said bath.

4. The method of recovering water-insoluble explosives in particulate form which comprises immersing a solid explosive containing trinitroluene as the binding agent in an agitated water bath containing 0.005 to 0.20 part by weight of a protective colloid per each 100 parts water at a temperature in the range of from about 85 C. to 98 C. until said trinitrotoluene is molten and the explosive is subdivided into small particles, thereafter while maintaining the agitation cooling the bath to a. temperature not greater than about C. and separating the resulting solidified particles of explosive from said bath.

5. The method of recovering water-insoluble explosives in particulate form which comprises immersing a trinitrotoluene explosive substantially free of volatile solvent in a water bath containing 0.005 to 0.20 part by weight of a protective colloid per each 100 parts water at a temperature in the range from about C. to 98 C. until said trinitrotoluene is molten, agitating said bath to subdivide said explosive into particles, cooling said bath to a temperature not greater than about 70 C. while maintaining the agitation, and thereafter separating said particles of explosive from said bath.

vReferences Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,402,971 Schofield et al. l Jan. 10, 1922 2,247,392 Lindsley, Jr. July 1, 1941 2,375,175 Silk May 1, 1045 

1. THE METHOD OF RECOVERING WATER-INSOLUBLE EXPLOSIVES IN PARTICULATE FORM WHICH COMPRISES SUSPENDING THE EXPLOSIVE SUBSTANTIALLY FREE OF VOLATILE SOLVENT IN AN AGITATED WATER BATH AT A TEMPERATURE ABOVE THE MELTING POINT OF THE EXPLOSIVE AND CONTAINING 0.005 TO 0.20 PART BY WEIGHT OF A PROTECTIVE COLLOID FOR EACH 100 PARTS WATER TO PREVENT THE RESULTANT ADJACENT PARTICLES OF MOLTEN EXPLOSIVE FROM AGGLOMERATING, COOLING THE BATH WHILE MAINTAINING THE AGITATION TO A TEMPERATURE BELOW THE FREEZING POINT OF THE EXPLOSIVE, AND THEREAFTER SEPARATING THE RESULTING SOLIDIFIED PARTICLES OF EXPLOSIVE FROM SAID BATH. 